1. Field of the Invention
The present invention relates to a lens guide apparatus that supports a lens holder of a camera or the like movably in an optical axis direction.
2. Related Background Art
Among conventional lens guide apparatuses of this type, there is a lens guide apparatus that moves a lens holder forward and backward with respect to an optical axis direction in the following manner. That is, a lead screw is rotated using a stepping motor or the like as a drive source, and a lens holder moves forward and backward with respect to an optical axis direction along with the rotation of the lead screw through a nut having a female screw portion that engages with the lead screw. There is also a lens guide apparatus that has a lens holder slidably fitted onto a guide axis and guides the lens holder along an optical axis direction, to thereby support a lens. In such a lens guide apparatus, a lead screw is directly provided for a drive axis of a motor. Accordingly, the lead screw rotates at the same time as the motor rotates. In conjunction with the rotation of the lead screw, the lens holder moves forward and backward with respect to the photographing optical axis direction. Also, the guide axis is supported by a support bottom board through press fitting (Japanese Patent Application Laid-Open No. 2001-66665). Further, there is a lens guide apparatus in which a lead screw and a guide axis are supported on both sides.
In the case of the lens guide apparatus described in Japanese Patent Application No. 2001-66665, however, a dimension thereof in the optical axis direction becomes large to some extent. This is because the lead screw is directly provided for the drive axis of the motor. Also, in the case of the lens guide apparatus in which the lead screw is supported on both sides, a lens barrel increases in size. This is because dedicated components for the both-side support are required, so the number of components is increased and a length in the optical axis direction should also be increased.
Further, in the case of the lens guide apparatus in which one-side support is achieved by press-fitting one end of the guide axis into the support bottom board, there is a problem in that optical performance is not guaranteed. This is because a press-fitting portion has a straight axis, so the guide axis is inclined at the time of the press fitting.